The advent of the ubiquitous era allows a user to freely access a network anywhere anytime without being aware of a terminal device, thus causing an explosive increase in network traffic. Particularly, at the request of a terminal device, a contents provider (CP) can provide large-volume contents via a network of any other internet service provider (ISP). In this case, due to concentration of traffic at internet exchange (IX) points and a resultant bottleneck, some problems such as an unstable network access and a degradation of a communication quality may be invited.
Introduced to solve such problems is a contents delivery network (CDN) for deploying a plurality of local caching devices at edges of an ISP network, transferring contents in advance, offered by a CP, to the local caching devices, and providing such contents in response to a user's request.
The CDN is composed of a load balancer (a global server load balancing, GSLB) and local caching devices. The load balancer selects, in response to a user's request, the local caching device capable of providing the best service. The local caching device previously stores contents in the order of a high caching hit and performs, in response to a user's request, pushing or caching of the stored contents.
By the way, in case of live streaming, the local caching device merely uses splitting due to the limit of having to provide contents in real time. Namely, the local caching device can merely distribute contents, received from the CP through one stream, to a number of terminal devices and cannot use pushing and caching as used in on-demand streaming.
Accordingly, even in case of live streaming that is incapable of using normal caching, technique to reduce a traffic concentration for the CP and a load of network traffic due to duplicate transmission of contents is needed.